The human mind is capable of formulating ideas both concrete and abstract. In order to record such ideas, human beings have historically written down their ideas using written language on a tangible medium. For instance, one common tangible medium is paper, which is still used in modern times. Using modern postal systems, written correspondence can be mailed over great distances allowing remote individuals to communicate.
In the computer age, human beings use computer systems in order to record written language on a computer-readable medium. Typically, the data representing such written language is stored in binary form, with a computer program (such as a word processor) representing such data in human readable form to a human being. To a human, the computer display simulates written correspondence such as a letter, paper, or the like. Such electronic writings may be digitally recorded as well as communicated using computer networks. Throughout this description, any type of written correspondence, whether recorded on a tangible or computer-readable medium, will be termed a “letter”.
Human beings author letters as they are capable of complex thought and applying intelligence to formulate a wide variety of written language. For instance, a human being can receive instructions on a certain type of letter to write, a goal of the letter, and a context, and formulate a letter of that type aimed at accomplishing the goal in the designated context. If those instructions are provided to different human beings with the same goal and context, another human being might generate another unique letter aimed towards accomplishing the same goal in the context, but containing different semantic and sentence structures altogether.
Computer systems can generate written language. However, such written language is very deterministic, and not context-based, nor rhetorical. Accordingly, it is often easy to tell when a human being has authored written language, as compared to automatically generated written language. Furthermore, computer generated language is often template-based, and thus given a particular goal or context, a semantically similar letter is generated to the point where it is hardly unique.